Engine or machine with at least one rotating piston running in an annular cylinder space



1962 F. ROHSMANN 3,057,544

ENGINE OR MACHINE WITH AT LEAST oNE ROTATING PISTON RUNNING IN ANANNULAR CYLINDER SPACE Filed April 28, 1959 5 Sheets-Sheet 1 IN V ENTOR. [1 /x Boys/v14 IVA/ 1962 F. ROHSMANN 3,057,544

ENGINE OR MACHINE WITH AT LEAST ONE ROTATING PISTON RUNNING IN ANANNULAR CYLINDER SPACE Filed April 28, 1959 5 Sheets-Sheet 2 I N V ENTOR. f2; /x lea/5M4 0y Oct. 9, 1962 F. ROHSMANN 3,057,

ENGINE OR MACHINE WITH AT LEAST ONE ROTATING PISTON RUNNING IN ANANNULAR CYLINDER SPACE Filed April 28. 1959 s Sheets-Sheet s Fig. i

I N V EN TOR.

/2'L/x @W/JMAMM Oct. 9, 1962 F. ROHSMANN 3,057,544

ENGINE OR MACHINE WITH AT LEAST ONE ROTATING PISTON RUNNING IN ANANNULAR CYLINDER SPACE 5 Shets-Sheet 4 Filed April 28, 1959r---:-ii:+----- 9, 1962 F. ROHSMANN 3,057,544

ENGINE OR MACHINE WITH AT LEAST ONE ROTATING PISTON RUNNING IN ANANNULAR CYLINDER SPACE Filed April 28. 1959 5 Sheets-Sheet 5 iifi tes

The present invention relates to an engine or machine with at least onerotating piston running in an annular cylinder space.

Engines as well as machines can be divided basically into rotatingmachines or engines and into reciprocating machines or engines providedwith pistons. In the ranges of smaller performances, smaller transportquantities and higher pressures, the rotating machines or engines are inferior to the reciprocating machines or engines as to their efiiciency.On the other hand the rotating machines or engines can be manufacturedin these ranges considerably cheaper and they are also more reliable intheir function as well as smaller and lighter. Rotating machines operatewith less vibrations than reciprocating machines. Finally, in therotating machines the work medium, eg, the steam, remains free oflubricating oil and can therefore be used further after having given itsoutput (e.g. for heating purposes).

It has already been proposed to provide an engine, which unites theadvantages of the reciprocating engines with those of the rotatingengines. In such a known engine with a piston rotating in an annularcylinder space, the closing of the cylinder space behind the piston wasto be effected by rotating discs arranged in the annular cylinder space,which were provided with holes for the passing of the piston. Thecylinder space was thus closed after the passing of the piston by therotating disc, so that a work medium, e.g. steam, could be fed into thecylinder space through valves, where it expanded. But with such rotatingdiscs a favourable closing of the cylinder space could not be obtained,so that the efficiency of such an engine is very low. This is the reasonwhy it was not possible up to now to provide an engine or a machine,which unites the advantages of the rotating and the reciprocatingengines or machines.

The present invention solves this problem by employing the concept of anengine or machine with at least one piston rotating around its axle andcircling in an annular cylinder space.

In carrying out the invention the lateral walls of the annular cylinderspace parallel to the axis of the rotating piston are arranged asuniformly curved rolling of surfaces, e.g. cycloides, whereby the apexesof the curvatures are opposed to each other to form at least one narrowspot, the width of which is exactly adapted to the cross section of amassive sealing fin arranged as a ring sector, which is integral in thecircling movement with the rotating piston, which besides is moved in auniform rotation around its axle by means of a suitable gearingarrangement.

In this way a sealed off expansion or compression space is created atall times in the annular cylinder space, without an oscillating movementbeing necessary; the necessary movements are absolutely uniform, i.e.without any accelerations or retardations.

In this connection the annular cylinder space is closed off for itssealing by an uninterrupted annular wall, which corresponds in itsmovement with the circling movement of the rotating piston and isprovided with sealed-off bearings for the axle of the rotating piston.

It is possible to arrange the annular cylinder space in a stationarymanner, while the annular wall with the rotating piston and the sealingfin rotates and the axle of the 3,957,544 I Patented Oct. 9, 1962 "icerotating piston is provided with a counter gear wheel rolling'ofi on astationary gear wheel.

A particularly advantageous arrangement of the machine or engine is,however, achieved, if the annular cylinder space rotates together withthe main shaft and the sealing fin as well as the rotating pistonrotating around its axle are stationary together with the annular wall.

In the case of a stationary cylinder space the rotating drive of therotating piston is effected in such a way, that on the axle of therotating piston a gear wheel is arranged, which engages with astationary gear wheel.

In case of the rotating cylinder space, there is arranged, on thecontrary, a gear wheel on the axle of the rotating piston, which is inconnection with a gear wheel rotating together with the main shaft.

A particularly simple arrangement of the machine is reached by the factthat the axle of the rotating piston is arranged in parallel to the mainshaft and the ring-shaped cylinder space is limited by two flat wallsstanding perpendicularly to the main shaft and by two cycloid-shapedrunning walls. As far as, however, a series of such machines or enginesare arranged adjacent to each other, the arrangement of the machine orengine must be provided in such a way, that the axle of the rotatingpiston is arranged perpendicularly to the main shaft and the annularcylinder space is limited by two cycloid-shaped walls perpendicular tothe main shaft and by two walls, arranged as ball ring surfaces.

The necessary inlet or outlet openings for the passing of the workmedium, e.g. of the steam, can be arranged in the walls which areperpendicular to the axle of the rotating piston.

In the case of the stationary ring-shaped cylinder space it isadvantageous, if these necessary inlet and outlet openingsfor thepassage of the work medium are arranged in the stationary wall which isperpendicular to the axle of the rotating piston.

In the ease of the rotating annular cylinder space it is, on thecontrary, possible, that the necessary inlet and outlet openings for thepassage of the work medium, e.g. the steam, are arranged in thestationary ring wall.

In this latter embodiment of the machine or engine a particularly highefliciency is attained, if the sealing fin has a section filling out thenarrow spot, while the thickness of the rotating piston is smaller thanthe inner width of the narrow spot and if furthermore the sealing fin isinterrupted only with the length of the rotating piston and the ends ofthe sealing fin are configurated as sealing surfaces cooperating withthe rotating piston ends. It is preferable, that the inlet and outletopenings necessary for the passage of the work medium are arrangedbeside the radial symmetrical plane of the machine in a wallperpendicular to the axle of the rotating piston.

The invention is to be elucidated further with a reference to thedrawings, which illustrates some embodiments of the device according tothe invention.

FIG. 1 is a first embodiment of the machine with stationary annularcylinder space diagrammatically in side elevation, the lateral wallbeing broken away,

FIG. 2 illustrates a further embodiment of the machine with rotatingannular cylinder space, likewise diagrammatically in side elevation,

FIG. 3 is a diagrammatic perspective view of the machine of FIG. 1 withparts being broken away to show other parts with greater clarity,

FIG. 4 is a diagram illustrating the ring cylinder space becomingnarrower with the rotating piston in the different operationalpositions,

FIG. 5 is an axial sectional view through the machine according to athird embodiment, in which the axles of the rotating pistons are inparallel with the main shaft and the ring cylinder space rotates aroundthe main shaft,

FIG. 6 is an axial sectional view through the machine according to afurther example, in which the axle of the rotational piston is arrangedperpendicular to the main shaft and the ring cylinder space rotates, and

FIG. 7 is a view of the narrow spot in the direction longitudinal to theaxle of the rotating piston to a greater scale.

The machine is provided with a main shaft 1 and an annular cylinderspace 2 which is arranged concentrically to this shaft, is closed, andvaries continuously in its section, being limited laterally bycycloid-shaped lateral walls 3 (cf. e.g. FIGS. 3 and 4). The lateralwalls 3 approach thus each other and form in this way one or severalnarrow spots 4. According to the arrangement of the machine theselateral walls 3 can be flat in radial position or they may be arcuated.

In the cylinder space 2 a sealing fin 5 is arranged, which is shorter orlonger according to the number of narrow spots. The thickness of thissealing fin is adapted to the section of the cylinder space 2 (cf. e.g.FIGS. 3 and 7). The sealing fin can either touch the lateral walls 3 inthe narrow space 4 or can be separated from them by very narrow slots.

Furthermore, there is arranged in the cylinder space 2 a rotating piston7, including a vane rotating round its shaft 6, which touches the twolateral walls 3 in every work position or is separated from it at themost by a very narrow adjustable slot. As is shown diagrammatically inFIGS. 1 and 2 the rotating piston 7 is rotated by means of gear wheels 8or 9 from the main shaft 1 in such a way, that the rotating pistonexecutes an absolutely uniform movement round its axle and closes orseals off the variable ring cylinder space in every position, but alsopasses easily through the narrow spot 4.

The sealing fin 5 and the rotational piston 7 move thus in commonrelative to the cylinder space 2 and form together in the course of therotation of the machine always again a closed off work room, which islimited on the one hand by the cylinder wall 3, on the other hand by thesealing fin 5 in the narrow spot 4, and further through the outerlimitation surface 10 and the inner limitation surface 11 of thecylinder space 2 and finally by the rotating piston 7, which by means ofits surfaces seals off the lateral and outer and inner limitationsurfaces of the annular cylinder space 2.

FIG. 1 shows a first embodiment of such a machine, in which the cylinderspace 2 is arranged stationary, while the sealing fin 5 and the rotatingpiston 7 rotates together, with the main shaft '1 and the rotation axle6 of the rotation piston 7 carries a counter gear wheel 12 rolling offon the stationary gear wheel 8. The inner limitation surface 11 formsthe bottom of the cylinder space 2 and is connected integrally with themain shaft 1 and carries besides the bearing 13 for the rotating piston7 and the sealing fin 5.

In FIG. 2 a second embodiment of the new machine is represented, whichis different from the first in so far, as there the cylinder space 2rotates with the main shaft 1, while the sealing fin 5 as well as therotation piston 7 rotating round its axle 6 are stationary. In theexample according to FIG. 1 as well as FIG. 3 with stationary cylinderspace 2 a packing 22 is arranged between the stationary walls of thecylinder space and the rotating surface 11. In the embodiment accordingto FIG. 2 such a packing is found, on the contrary, between the outerstationary limitation surface 10'and the two lateral walls 3 rotatingtogether with the main shaft. The sealing fin 5 is in this case firmlyconnected with the outer limitation surface 10 and in the same way thislimitation surface 10 carries also the bearing 3 for the rotating piston1, the drive of which is shown diagrammatically in FIG. 2. V

The second execution according to FIG. 2 has an advantage in so far asthere the rotating piston 7 and its bearing are not submitted to anyadditional rotational forces. Besides, each formed lateral wall 3 of thecylinder space transfers power and output, while according to the firstembodiment the rotational piston 7 is the transmitting means of powerand output to the main shaft 1.

Near the narrow spot 4 there is, according to the type of the machine(engine or machine) seen in the rotational direction in front or behindit in suitable distances, the inlet, respectively, outlet openings 14(FIG. 7) respectively several such openings, which feed in the gaseousor liquid medium furnishing or absorbing the power, according to whetheran engine or a machine is involved. The outlet and inlet openings arearranged, according to the desired degree of expansion or compressionnearer or farther away from the narrow spot 4 in the rotationaldirection or against it. The inlet or outlet openin s can be arranged ina shiftable or modifiable manner, whereby also during the operation therelation of expansion and oblique stroke and/or the compression can bevaried, respectively, adjusted.

As far as the novel machine works as an engine, the narrow spot 4 isalways passed first by the rotational piston 7 and then closed by thesealing fin 2. If however, the new machine is to be used to executework, it is always the sealing fin 5 which passes the narrow spot firstand then the rotational piston 7 follows in passing each narrow spot 4.

In the shown embodiments there is illustrated only one narrow spot forsimplification purposes. It is, however, possible, that the annularcylinder space 2 can also have several narrow spots 4 as well as severalrotation pistons 7 and a corresponding number of sealing fins 5. It isalso favourable in some cases, to arrange several cylinder spacesconcentrically straight and/or obliquely laterally one above the otheror beside each other, whereby all Work on one and the same or severalseparate shafts in one axis direction. Thereby the cylinder spaces canbe used as engines and/or machines or in a mixed manner.

The last named possibility can be made use of if the machine is used asan internal combustion engine, whereby ring channels arranged at theside, above or behind are alternately or in groups used as engines ormachines (compressors).

In FIGS. 5 and 6 particularly advantageous embodiments of the novelmachine are shown.

The particularity in the embodiment acording to FIG. 5 consists in thefact that the axle 6 of the rotating piston 7 is arranged parallel tothe main shaft 1, whereby not only a particularly simple drive of theaxle 6 is obtained of the rotating piston 7, but also a very simpleconfiguration of the lateral walls 15 of the annular cylinder room 2.These lateral walls 15 can, it must be said, be arranged in thisembodiment in a completely plane manner, while the outer wall 146 andthe inner wall 17 of the cylinder space 2 are arranged as rolling offsurfaces with regular curvature, i.e. in the manner of cycloid surfaces.In the example according to FIG. 5 the cycloid surfaces 16 and 17 andthe plane lateral wall 15 form one integral part, which is keyed on themain shaft :1 by means of the hub 18 and rotates around it. The secondlateral side wall 15, which carries the bearing 13 for the rotatingpiston axle 6 is stationary, just as the wall 19, which serves as abearing for the main shaft 1. The wall 19 and the stationary lateralwall 15 can be led to a stationary support.

In the embodiment according to FIG. 5 a gear wheel 20 keyed on this axleis sufficient for the rotating of the rotating piston axle 6, which gearWheel is in engagement with a gear wheel 21 fastened onto the main shaft1.

The example according to FIG. 5 can also be varied in such a way, thatnot only one lateral surface 15 but the two side surfaces 15 arestationary, while the cycloid walls 16 and 17 rotate.

It is besides readily possible to rotate the lateral wall 15 carryingthe bearing 13 together with the main shaft 1 and to arrange thecylinder space 2 stationary, which is formed by the walls l6, l7 and 15.In this case the gear wheel 21 would not be connected with the mainshaft 1 but would be arranged in a stationary manner, so that the gearwheel meshes in its circling movement on the stationary gear Wheel 21and rotates thereby the rotating piston 7 in a uniform manner.

It is a feature of the embodiment according to FIG. 6, that the axle ofthe rotating piston 7 is arranged, it must be said, perpendicular to themain shaft 1, whereby, however, the cylinder space 2 rotates, which isformed by the lateral walls 23 and the inner Wall 24, which is arrangedas ball ring surface, so that the rotating piston 7 with itscorresponding sealing surface cannot lift off during the rotatingmovement around its axle -6 from the surface 24 in any place. Thesurface 24 passes over into a hub 25, which is again keyed on the mainshaft 1.

The cylinder space 2 is closed off by the outer wall 26, which isconfigurated in a stationary manner and is connected with the support 28by means of screws 27. This outer wall 26 has likewise in the inside asealing surface, which is in the form of a ball ring surface. Betweenthe outer wall 26 and the rotating lateral surfaces 23, which are ofcycloid-shaped configuration, packings 22 are arranged. The rotatingcylinder space 2 is completely closed in by stationary discs 28 and 29,which serve at the same time as a bearing of main shaft 1. The disc 29is connected rigidly by means of screws 30 with the outer wall 26.Furthermore the bearing .13 for the rotating piston axle 6 is screwedonto the outer wall 26. The drive of the rotating piston 7 isaccomplished done in this embodiment over an angle 31, driven by themain shaft 1 and through a shaft 32, gear wheels 33, 34 and 35, wherebythe gear wheel 35 is firmly connected with the axle 6 of the rotatingpiston. The main shaft 1 arranged in this case vertically is carried inthe support 28 by means of an axial bearing 36. It is, however, alsopossible to modify the embodiment according to FIG. 6 in such a manner,that the main shaft 1 is horizontal and the stationary lateral walls 29and 28 have an extension arranged at the support.

In the embodiment according to FIG. 7 it is shown in which way aparticularly high efiiciency of the machine can be reached. In this casethe sealing fin 5 is interrupted only in the length of the rotatingpiston 7. The ends 37 and 38 of the sealing fin 5 are arranged ascircular surface and cooperate in a sealing manner with the ends 39 and41} of the rotating piston 7. The rotating fin 5 is of such a section,that it completely closes the narrow spot 4. In the illustrated positionthe rotating piston 7, seals with its end 40 at the cycloid lateral wall3 and with its end 39 on the sealing surface 37 of the sealing fin 5, sothat in this way a very small completely sealed off working space 41 iscreated. If it be assumed that the machine is to be used as acompressor, then there is in this working space 41 arranged in one ofthe walls perpendicular to the rotating axle 6 of the piston 7 an outletvalve 14 in rotational direction directly before the apex of the narrowspot 4. This valve 14 can e.g. be arranged as a valve in the form of amushroom, as it is used in the construction of motor vehicles andcontrolled by means of cams. By the arrangement of this valve 14laterally from the radially symmetrical line of the machine there isonly a very small idle space left in the working space, so that a veryhigh compression can be reached. It must also be taken intoconsideration in this connection, that in this case the piston 7 is of asmaller thickness than the sealing fin 5.

There is furthermore shown in the embodiment according to FIG. 7 aposition of the rotating piston 7 in dotted lines, which is applicablefor that case, that the machine is to be used as an engine, e.g. a steamengine. For this case there is, seen in the rotating direction, directlybehind the narrow spot 4 an inlet valve 42, which can be constructed andcontrolled exactly as the cited outlet valve 14.

As far as the machine has to work as a machine, e.g. a compressor, thereis arranged in one of the walls of the cylinder space 2 near the narrowspot 4 and opposite to the outlet valve 14 an inlet slot, which can beopened.

As far as the machine works, however, e.g. as a steam engine, there isadjacent to the narrow spot 4 and opposite to the inlet valve 42 anoutlet slot, which can likewise be uncontrolled.

Experiments were made in order to find out in which ranges the novelmachine works most economically. The results showed that with a relationof the centrifugal speed of the rotating piston to the rotational speedof the rotating piston equal to or greater than eight excellent economicconstructions are possible.

No matter whether the novel device serves as an engine or as a machine,it is advantageous in order to reach an economically favourablesolution, to provide a cylinder space with several narrow spots and oneor more rotating pistons and one or more sealing fins or, still better,the arrangement of cylinder space adjacent to each other, likewise withone or several narrow spots each and one or several rotating pistons andone or several sealing fins.

If it is worked with two or several correspondingly arranged rotatingpistons and sealing fins, then it is possible also with one cylinderspace with only one single narrow spot and of course also with suchspaces with several narrow spots to arrange engines and machinesdirectly behind each other, e.g. in the diesel method the compression isarranged directly before the generating of power. Corresponding ofi?setting of engines and machines are likewise possible.

There is furthermore the possibility in the different constructions, toexpand without any difiiculty by one step or in several steps creatingpower or to compress absorbing power, respectively to Work in a mixedmanner. 'Ilhus a steam driven engine constructed in the novel manner canwork to several counter pressures with or without condensation, wherebythe single expansion relations can be made variable as alreadydescribed. The same is valid in a similar manner also for the use of thenovel device as a machine.

Various changes and modifications may be made without departing from thespirit and scope of the present invention and it is intended that thesemodifications and changes be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. An apparatus of the type disclosed, comprising a pair of spacedopposed cycloid shaped lateral walls defining therebetween an operatingspace and defining at least one narrow spot therebetween, a first one ofsaid walls being of relatively small radius of curvature and sharplycurved at said narrow spot and a second opposed wall being of relativelylarge radius of curvature and flatly curved at said narrow spot, a mainshaft extending normal to said lateral walls, a sealing fin disposedabout said main shaft and located between said lateral walls, and apiston including a piston shaft extending normal to said main shaft andfurther including a piston vane having opposite end edges engaging saidlateral walls during operation, said vane being rotatable about its ownaxis, said sealing fin having an opening therein, said vane beingdisposed in said opening and having its axis disposed closer to saidsecond wall than said first wall at a location adjacent said narrowspot, an annular wall closing said operating space, and an inlet and anoutlet opening in said annular wall connected into said operating spaceat spaced locations adjacent said narrow spot.

2. An apparatus of the type disclosed, comprising a pair of spacedcycloid shaped lateral walls defining therebetween an operating spaceand defining at least one narrow spot therebetween, a first one of saidwalls being of relatively small radius of curvature and sharply curvedand a second opposed wall being of relatively large radius of curvatureand flatly curved at said narrow spot, a main shaft extending normal tosaid lateral walls, a sealing fin disposed about said main shaft andlocated between said lateral walls, a piston including a piston shaftextending normal to said main shaft and further including a piston vanehaving opposite end edges engaging said lateral walls, said sealing finhaving an opening therein, said vane being disposed in said opening andbeing rotatable about its own axis and having its axis disposed closerto said second wall than said first wall at a location adjacent saidnarrow spot, an annular wall closing said operating space, an inlet andan outlet opening in said annular wall connected into said operatingspace at spaced locations adjacent said narrow spot, and means connectedto said main shaft and said piston shaft for rotating said piston tomaintain a positive relationship between said vane and said lateralwalls.

3. An apparatus of the type disclosed, comprising a pair of spacedcycloid shaped lateral walls defining therebetween an annular shapedcylinder space having at least one narrow spot, a first one of saidWalls being of relatively small radius of curvature and sharply curvedat said narrow spot and a second opposed wall being of relatively largeradius of curvature and flatly curved at said narrow spot, a main shaftextending normal to said lateral walls at the centers thereof, a massivesealing fin disposed about said main shaft and located between saidlateral walls, said sealing fin having a thickness substantially thesame as the width of said narrow spot, a piston including a piston shaftextending normal to said main shaft and further including a piston vanehaving opposite end edges engaging said lateral walls, said sealing finhaving an opening therein, said vane being disposed in said opening andhaving its axis disposed closer to said second wall at a locationadjacent said narrow spot, an annular wall closing said operating space,an inlet and an outlet opening in said annular wall connected into saidoperating space at spaced locations adjacent said narrow spot, said vanebeing rotatable about its own axis with said main shaft, and a gearingarrangement connected to said main shaft and said piston shaft forrotating said piston to maintain a positive relationship between saidvane and said lateral walls.

4. An apparatus according to claim 3, wherein the annular cylinder spaceis arranged to be stationary, while said piston and said sealing finrotate, said piston shaft being provided with a counter gear wheelforming a part of said gearing arrangement, a stationary gear wheel onone of said lateral walls, said counter gear wheel meshing with saidstationary gear wheel.

5. An apparatus according to claim 3, wherein said sealing fin hasconcave peripheral edges defining said openin g, said vane having athickness less than the width of said narrow spot, said end edges ofsaid vane engaging said concave peripheral edges of said sealing finwhen said vane passes through said narrow spot.

6. An apparatus according to claim 5, wherein said annular cylinderspace is sealed otf by a peripheral annular wall, said gearingarrangement moving said annular wall to coincide with the circlingmovement of the rotating vane, said annular wall having a sealed olfbearing for the axle of the rotating piston.

7. A fluid working device comprising a main shaft, cylinder wall meansadjacent said main shaft including spaced opposing curved wallsextending radially outwardly from said shaft defining an operating spacetherebetween, said walls converging at at least one narrow constrictedarea, a first one of said curved walls being of relatively large radiusof curvature and relatively flat at said constricted area and a secondopposed wall being of relatively small radius of curvature andrelatively sharply curved at said constricted area, a piston having avane rotatable about its own axis and about the axis of said shaft andlocated between said curved walls, the axis of rotation of said pistonbearing closer to said first wall than said second wall at saidconstricted area, said piston having vanes of a thickness less than thedistance between said curved walls at said constricted area and havingportions in contact with said opposite curved walls during operation, asealing fin disposed between said walls on each side of said piston,said curved walls and said piston and said sealing fin being operativelyconnected to said main shaft for relative rotation between said pistonand sealing fin on the one hand and said curved walls on the other hand,and fluid access means located at said constricted area including inletand outlet connections extending radially inwardly into said operatingspace at circumfercntially spaced locations adjacent said constrictedarea.

8. A fluid working device according to claim 7, wherein said device is acompressor and said piston and said sealing fin are rotated so that saidpiston approaches said constricted area first during each cycle ofoperation.

9. A fluid working device according to claim 7, wherein said device isan engine and said piston and said sealing fin are rotated so that saidsealing fin approaches said constricted area first during each cycle ofoperation.

10. A fluid working device according to claim 7, wherein the axis ofsaid piston is substantially perpendicular to said main shaft.

11. A fluid working device according to claim 7, wherein said pistonaxis is substantially parallel to said main shaft.

References Cited in the file of this patent UNITED STATES PATENTS1,101,329 Reaugh June 23, 1914 1,136,976 Reaugh Apr. 27, 1915 1,467,944Mason Sept. 11, 1923 1,580,808 Borden Apr. 13, 1926 1,831,263 Ross Nov.10, 1931 FOREIGN PATENTS 596,888 France Aug. 17, 1925 1,149,144 FranceJuly 8, 1957 269,617 Great Britain Apr. 25, I927

